CVE-2022-44617 - LibXpm Width and Large Height Processing Flaw Resulting in a Denial of Service Attack

CVE-2022-44617 is a critical vulnerability discovered in the open-source X PixMap (XPM) image file format library, libXpm. This post provides a detailed analysis of the vulnerability, the exploit process, and links to original references, along with code snippets that demonstrate the flaw. The vulnerability lies in the way libXpm processes image files with a width of  and a very large height which could lead to an infinite loop, resulting in a Denial of Service (DoS) attack in the applications linked to the library.

Background

LibXpm is a widely used library for handling XPM image file format processing in various applications like image viewers, web browsers, and image manipulation tools. By exploiting the vulnerability in the libXpm, an attacker could maliciously create XPM image files and cause the application linked to the library to enter an infinite loop, thereby causing a DoS attack.

Exploit Details

The root cause of the vulnerability (CVE-2022-44617) is that when the library processes an XPM file with a width of  and a very large height, some parser functions will be called repeatedly, eventually leading to an infinite loop. The infinite loop subsequently exhausts the resources of the machine, causing a Denial of Service attack.

Here's a code snippet that illustrates the flaw in libXpm

// filename: libXpm.c

int parse_xpm_image(XpmImage *image) {
    int result;
    unsigned int height = ;

    // ... other code ...

    // Process XPM image data
    while (next_line != NULL) {
        line = next_line;
        parse_whc_value(&line, &width, &height, &colors);

        if (width == ) {
            // Infinite loop if width is  AND height is very large
            next_line = parse_image_data(image, height);
        } else {
            next_line = parse_color_data(image, colors);
        }
    }

    // ... other code ...

    return result;
}

As seen in the code snippet above, the parse_xpm_image function processes the XPM image data line by line. If the width of the image data is , the program enters into an infinite loop when the height is extremely large. This causes the application linked to the library to hang indefinitely, resulting in a Denial of Service.

Original References

1. CVE-2022-44617 - NIST National Vulnerability Database
2. LibXpm Official Repository
3. XPM Image File Format

Mitigation

To mitigate CVE-2022-44617, users are urged to patch their libXpm library immediately to the latest version available from the official repository: libXpm Patches. Additionally, developers should implement proper input validation checks for XPM image width and height in their applications to avoid malformed XPM images causing infinite loops and potential Denial of Service attacks.

In conclusion, the CVE-2022-44617 vulnerability highlights the importance of rigorous input validation and how a faulty implementation can lead to Denial of Service attacks. By keeping our libraries up-to-date and following best practices in application development, we can prevent such security flaws from becoming critical threats.

Timeline

Published on: 02/06/2023 23:15:00 UTC
Last modified on: 03/03/2023 15:15:00 UTC